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RE: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages

From "Elliott, Robert (Persistent Memory)" <elliott@hpe.com>
Newsgroups linux.kernel
Subject RE: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of poison pages
Date 2017-06-24 00:30 +0200
Message-ID <tVFfr-80b-7@gated-at.bofh.it> (permalink)
References <tT5SN-50W-5@gated-at.bofh.it> <tU9hE-674-27@gated-at.bofh.it> <tURVo-Rb-33@gated-at.bofh.it>
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> > > +	if (set_memory_np(decoy_addr, 1))
> > > +		pr_warn("Could not invalidate pfn=0x%lx from 1:1 map \n",

Another concept to consider is mapping the page as UC rather than
completely unmapping it.

The uncorrectable error scope could be smaller than a page size, like:
* memory ECC width (e.g., 8 bytes)
* cache line size (e.g., 64 bytes)
* block device logical block size (e.g., 512 bytes, for persistent memory)

UC preserves the ability to access adjacent data within the page that
hasn't gone bad, and is particularly useful for persistent memory.

---
Robert Elliott, HPE Persistent Memory

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Thread

Re: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings  of poison pages "Luck, Tony" <tony.luck@intel.com> - 2017-06-21 19:50 +0200
  RE: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of  poison pages "Elliott, Robert (Persistent Memory)" <elliott@hpe.com> - 2017-06-21 22:00 +0200
    RE: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings  of poison pages "Luck, Tony" <tony.luck@intel.com> - 2017-06-21 22:20 +0200
  Re: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings  of poison pages Borislav Petkov <bp@suse.de> - 2017-06-22 11:40 +0200
    git send-email (w/o Cc: stable) "Luck, Tony" <tony.luck@intel.com> - 2017-06-30 00:20 +0200
      Re: git send-email (w/o Cc: stable) Borislav Petkov <bp@suse.de> - 2017-06-30 09:10 +0200
  RE: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of  poison pages "Elliott, Robert (Persistent Memory)" <elliott@hpe.com> - 2017-06-24 00:30 +0200
    Re: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings of  poison pages Dan Williams <dan.j.williams@intel.com> - 2017-06-28 00:10 +0200
    RE: [PATCH] mm/hwpoison: Clear PRESENT bit for kernel 1:1 mappings  of poison pages "Luck, Tony" <tony.luck@intel.com> - 2017-06-28 00:10 +0200

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